1. Field of the Invention
The present invention relates generally to trigger actuated sprayers for dispensing liquid from a container, particularly to the trigger assembly for such a sprayer, and to methods for assembling a complete device.
2. Description of the Related Art
Trigger actuated sprayers which dispense liquids in response to depression of a trigger are well known. The sprayers have received wide consumer acceptance and appeal due to the ease of handling the sprayer, the efficiency with which the sprayer dispenses liquid, and the convenience of using such a sprayer. Typically, the sprayers are used to dispense a variety of liquid products, such as cleaning solutions, cosmetics, toiletries, agricultural and industrial products.
Such trigger sprayers have a nozzle for dispensing either a spray or a stream of the liquid products. As part of the design of the sprayer, the aim point of the nozzle must be kept relatively constant as the trigger handle is depressed. Generally, three alternatives are available to ensure that the aim point does not substantially change. The alternatives are illustrated schematically in FIGS. 1, 2 and 3.
First, as illustrated in FIG. 1, nozzle 101 may be fixed onto the trigger sprayer body so that it does not move as trigger handle 102 is operated. The trigger handle in a device using this alternative compresses a separate pump 103 in the direction of the arrow. An unshown passage communicating with the nozzle leads the liquid from the pump to the nozzle. U.S. Pat. No. 3,061,202 to Tyler illustrates a trigger sprayer using a fixed nozzle and a separate pump.
The second alternative to ensure that the aim point of the nozzle is kept relatively constant is illustrated in FIG. 2. In this alternative, nozzle 101 is formed integrally with pump 103. The nozzle is formed so that the aim point coincides with the pumping axis of the pump. Thus, as trigger handle 102 is depressed to operate the pump, the nozzle moves back along the pumping axis, in the direction of the arrow, thereby maintaining a constant aim point. U.S. Pat. No. 3,701,478 to Tada illustrates a trigger sprayer in which the nozzle moves back along the pumping axis as the trigger handle is depressed.
The third alternative to keep the aim point of the nozzle relatively constant is to mount the nozzle at the end of the pump and to aim the nozzle at an angle relative to the pumping axis. As shown in FIG. 3, nozzle 101 is mounted at a right angle relative to pump 103. As trigger handle 102 is operated, the pump is depressed and the nozzle moves down in the direction of the arrow with the pump. Although the aim point of the nozzle in this alternative moves slightly in the vertical direction, for all practical purposes the aim point is constant. U.S. Pat. No. 4,077,549 to Beard illustrates a trigger sprayer in which the nozzle descends as the trigger handle is depressed.
In all these designs, however, when the trigger handle is depressed, the radial distance between the pivot point for the handle 106 and the depression point of the handle (between cam 105 and sliding surface 104) changes. This is shown schematically in FIG. 4a. When the trigger handle is in a depressed position, indicated by the solid lines, the radial distance L1 between the pivot point P of the trigger handle and the depression point D of the trigger handle is different than the radial distance when the trigger handle is released. The released position is indicated by the dotted lines in FIG. 4a. As depicted in FIG. 4a, the released distance L2 is considerably less than the depressed distance L1. Thus, to allow the aim point of the nozzle to remain constant while the trigger handle is depressed, a special structure must be utilized to accommodate this change in radial distance.
Although a variety of special structures have been adapted to accommodate the change in radial distance, the usual structure consists of a cam and a sliding surface which allows the trigger handle to pivot about its pivot point while maintaining the nozzle (or the pump in the FIG. 1 alternative) in its desired orientation. A cam and a sliding surface are denoted by numerals 105 and 104, respectively, in FIGS. 1, 2 and 3. By way of further example, a cam and a sliding surface may be seen in FIG. 3, reference numerals 40 and 41 in Tyler; FIG. 2, reference numerals 54 and 55 in Tada; and FIG. 1, reference numerals 17 and 26 in Beard.
Another structure for accommodating the change in radial distance is illustrated in U.S. Pat. No. 4,077,548 to Beard, which utilizes a complicated series of pivot points and levers, as shown in FIG. 5 therein.
However, the designs for such structures are involved and require extremely close tolerances to operate properly. The structures are complicated and have a high parts count. Often, the structures are fragile, due to small parts being subjected to high stress. Moreover, since the trigger handle is usually supported at only one pivot point, both the pivot point and the trigger handle are highly susceptible to damage.
Since the parts count is high, it is extremely difficult inexpensively to manufacture the device and to assemble a finished product. Close tolerances of many of the parts also cause assembly of the trigger sprayer to be extremely difficult, costly and time consuming. The insertion of the trigger pivot point into its pivot assembly and the alignment of the trigger handle with the pump are particularly difficult operations.
The high parts count and the need for close tolerances also lead to problems with leakage of the contents of the container when the pump is not being used, or when the container is inverted.